The present invention is directed to a protective plate for a bicycle chain and, more particularly, to a protective plate that is mounted near the front derailleur of the bicycle to prevent the chain from falling from the large sprocket and which is capable of positioning the front derailleur on the frame.
Some bicycles are equipped with three front chainrings connected to the front pedals and a plurality of rear sprockets attached to the rear wheel of the bicycle. A chain is connected between a selected front chainring and a selected rear sprocket to provide driving force from the pedals to the rear wheel. A front derailleur is used to position the chain on the selected front chainring, and a rear derailleur is used to position the chain on the selected rear sprocket. The various combinations of front and rear sprockets provide a wide range of gear ratios to accommodate a wide range of riding conditions.
If the front derailleur is not adjusted properly, there is a risk that the chain will fall from the smallest chainring when the chain is being shifted from the middle chainring to the smallest chainring. As a result, the chain often jams between the smallest sprocket and the bicycle frame, thus requiring the rider to dismount the bicycle and reattach the chain to the sprocket. Since the chain often jams between the smallest sprocket and the bicycle frame with much force, unjamming the chain can be very difficult. Thus, it is desirable to prevent such jamming if possible.
Adjusting the front derailleur includes properly setting the vertical position of the front derailleur on the seat tube. This can prove very difficult and time consuming, since very close tolerances are usually required for proper operation. As a result, the front derailleur frequently is not positioned correctly.